When messages are passed from one server to another through SMTP, Exchange Edge, and Mailbox servers, add custom
X-Header fields to the message header. These headers can contain a variety of information, such as mail server IP addresses, spam confidence levels (SCL), content filtering results, and rule processing statuses. Header firewalls are used to remove these custom
X-Header fields so that unauthorized sources cannot obtain detailed information about your messaging environment. In this recipe, you'll learn how to use the Exchange Management Shell to implement a header firewall that prevents the disclosure of the internal information sent to an external source.
One of the most common uses of a header ...